https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96768
Bug ID: 96768
Summary: -mpure-code produces switch tables for thumb-1
Product: gcc
Version: 10.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: clyon at gcc dot gnu.org
Target Milestone: ---
As discussed in PR94538, -mpure-code produces switch tables for thumb-1.
int f2 (int x, int y)
{
switch (x)
{
case 0: return y + 0;
case 1: return y + 1;
case 2: return y + 2;
case 3: return y + 3;
case 4: return y + 4;
case 5: return y + 5;
}
return y;
}
Compiled with -O2 -mpure-code,
-mcpu=cortex-m0:
f2:
cmp r0, #5
bhi .L9
movs r2, #:upper8_15:#.LC0
lsls r2, #8
adds r2, #:upper0_7:#.LC0
lsls r2, #8
adds r2, #:lower8_15:#.LC0
lsls r2, #8
adds r2, #:lower0_7:#.LC0
ldr r2, [r2]
lsls r0, r0, #2
ldr r3, [r2, r0]
mov pc, r3
.section .rodata
.align 2
.L4:
.word .L9
.word .L8
.word .L7
.word .L6
.word .L5
.word .L3
.section .text,"0x20000006",%progbits
.L3:
adds r0, r1, #5
.L1:
@ sp needed
bx lr
.L8:
adds r0, r1, #1
b .L1
.L7:
adds r0, r1, #2
b .L1
.L6:
adds r0, r1, #3
b .L1
.L5:
adds r0, r1, #4
b .L1
.L9:
movs r0, r1
b .L1
For cortex-m23:
f2:
cmp r0, #5
bhi .L9
movw r2, #:lower16:.LC0
movt r2, #:upper16:.LC0
ldr r2, [r2]
lsls r0, r0, #2
ldr r3, [r2, r0]
mov pc, r3
For reference, for cortex-m3:
f2:
cmp r0, #3
beq .L2
ble .L11
cmp r0, #4
beq .L7
cmp r0, #5
bne .L9
adds r0, r1, #5
bx lr
.L11:
cmp r0, #1
beq .L4
cmp r0, #2
bne .L9
adds r0, r1, #2
bx lr
.L2:
adds r0, r1, #3
bx lr
.L7:
adds r0, r1, #4
bx lr
.L4:
adds r0, r1, #1
bx lr
.L9:
mov r0, r1
bx lr
